Organic electroluminescent materials and devices

ABSTRACT

In certain embodiments, the invention provides boron-nitrogen heterocycles having Formula (I): 
                         
wherein one of the E 1  and E 2  is N, and one of the E 1  and E 2  is B; wherein E 3  and E 4  is carbon; wherein ring Y and ring Z are 5-membered or 6-membered carbocyclic or heterocyclic aromatic ring fused to ring X; wherein R 2  and R 3  represent mono, di, tri, tetra substitutions or no substitution; wherein R 2  and R 3  are each independently selected from various substituents; and wherein any two adjacent R 2 , and R 3  are optionally joined to form a ring, which may be further substituted. In certain embodiments, the invention provides devices, such as organic light emitting devices, that comprise such boron-nitrogen heterocycles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser. No. 61/704,837, filed Sep. 24, 2012, the entire contents of which are incorporated herein by reference.

JOINT RESEARCH AGREEMENT

The claimed invention was made by, on behalf of, and/or in connection with one or more of the following parties to a joint university corporation research agreement: Regents of the University of Michigan, Princeton University, University of Southern California, and the Universal Display Corporation. The agreement was in effect on and before the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within the scope of the agreement.

FIELD OF THE INVENTION

The present invention relates to organic light emitting devices (OLEDs). In particular, the invention relates to boron-nitrogen heterocycles that may have improved electrochemical and photophysical properties, especially when used in an OLED.

BACKGROUND

Opto-electronic devices that make use of organic materials are becoming increasingly desirable for a number of reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have performance advantages over conventional materials. For example, the wavelength at which an organic emissive layer emits light may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting. Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full color display. Industry standards for such a display call for pixels adapted to emit particular colors, referred to as “saturated” colors. In particular, these standards call for saturated red, green, and blue pixels. Color may be measured using CIE coordinates, which are well known to the art.

One example of a green emissive molecule is tris(2-phenylpyridine) iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond from nitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. “Small molecule” refers to any organic material that is not a polymer, and “small molecules” may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the “small molecule” class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone. Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or phosphorescent small molecule emitter. A dendrimer may be a “small molecule,” and it is believed that all dendrimers currently used in the field of OLEDs are small molecules.

As used herein, “top” means furthest away from the substrate, while “bottom” means closest to the substrate. Where a first layer is described as “disposed over” a second layer, the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is “in contact with” the second layer. For example, a cathode may be described as “disposed over” an anode, even though there are various organic layers in between.

As used herein, “solution processible” means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as “ancillary” when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled in the art, a first “Highest Occupied Molecular Orbital” (HOMO) or “Lowest Unoccupied Molecular Orbital” (LUMO) energy level is “greater than” or “higher than” a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level. Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A “higher” HOMO or LUMO energy level appears closer to the top of such a diagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled in the art, a first work function is “greater than” or “higher than” a second work function if the first work function has a higher absolute value. Because work functions are generally measured as negative numbers relative to vacuum level, this means that a “higher” work function is more negative. On a conventional energy level diagram, with the vacuum level at the top, a “higher” work function is illustrated as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow a different convention than work functions.

More details on OLEDs, and the definitions described above, can be found in U.S. Pat. No. 7,279,704, which is incorporated herein by reference in its entirety.

SUMMARY OF THE INVENTION

In at least one aspect, the invention provides boron-nitrogen heterocycles having the Formula (I):

wherein one of the E₁ and E₂ is N, and one of the E₁ and E₂ is B; wherein E₃ and E₄ is carbon; wherein ring Y and ring Z are 5-membered or 6-membered carbocyclic or heterocyclic aromatic ring fused to ring X; wherein R₂ and R₃ represent mono, di, tri, tetra substitutions or no substitution; wherein R₂ and R₃ are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R₁ is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein any two adjacent R₂, and R₃ are optionally joined to form a ring, which may be further substituted.

In some embodiments, E₁ is B, and E₂ is N. In some other embodiments, E₁ is N, and E₂ is B.

In some embodiments, ring Y is selected from the group consisting of:

wherein E₅ is selected from the group consisting of NR, O, S, and Se; and wherein R is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. In some further embodiments, ring Y is

In some embodiments, ring Z is selected from the group consisting of:

wherein E₅ is selected from the group consisting of NR, O, S, and Se; and wherein R is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. In some further embodiments, ring Z is

In some embodiments, R₁, R₂, and R₃ are independently selected from the group consisting of phenyl, pyridine, triazine, pyrimidine, phenanthrene, naphthalene, anthracene, triphenylene, pyrene, chrysene, fluoranthene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene, each of which may be further substituted.

In some embodiments, the boron-nitrogen heterocycles have the formula

where the variables have the meanings defined above.

In some embodiments, the boron-nitrogen heterocycles have Formula (II):

wherein R²¹ and R²² are independently are aryl or heteroaryl, each of which may be further substituted; R²³ and R²⁴ are independently aryl or heteroaryl, each of which may be further substituted; and G is arylene, heteroarylene, or combinations thereof. In some such embodiments, G is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is

In some embodiments, the bron-nitrogen heterocycle is a compound having Formula (III):

wherein R³¹ and R³² independently are aryl or heteroaryl, which may be further substituted; and wherein G¹, G², and G³ independently are arylene or heteroarylene. In some such embodiments, G¹, G², and G³ independently are phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is: which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (IV):

wherein G⁴ is arylene or heteroarylene. In some such embodiments, G⁴ is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (V):

wherein R⁵¹ is aryl or heteroaryl. In some such embodiments, R⁵¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.

In some embodiments, the born-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (VI):

wherein R⁶¹ and R⁶² independently are aryl or heteroaryl. In some such embodiments, R⁶¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof; and R⁶² is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (VII):

wherein R⁷¹ and R⁷² independently are aryl or heteroaryl. In some such embodiments, R⁷¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof; and R⁷² is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (VIII):

wherein G⁵ is arylene or heteroarylene; and R⁸¹ and R⁸² are independently aryl or heteroaryl, each of which is substituted with at least one acyclic or cyclic aliphatic substituent. In some such embodiments, G⁵ is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In another aspect, the invention provides devices that include boron-nitrogen heterocycles, such as those described in the foregoing paragraphs. In some embodiments, the invention provides a first device comprising a first organic light emitting device, which further comprises: an anode; a cathode; and an organic layer disposed between the anode and the cathode, which comprises a boron-nitrogen heterocycle according to any of the above embodiments. In some embodiments, the first device is a consumer product. In some embodiments, the first device is an organic light emitting device (OLED). In some embodiments, the first device comprises a lighting panel.

The boron-nitrogen heterocycles can serve various roles within a device. In some embodiments, the first device comprises an organic layer that is an emissive layer, where the emissive layer comprises an emissive dopant, which is a boron-nitrogen heterocycle of any of the above embodiments. In some such embodiments, the first device is a delayed fluorescence device.

In some other embodiments, the first device comprises an organic layer that is an emissive layer, and also comprises a host. In some such embodiments, the host is a boron-nitrogen heterocycle of any of the above embodiments. In some such embodiments, the organic layer comprises an emissive dopant. In some embodiments, the emissive dopant is a fluorescent dopant. In some embodiments, the emissive dopant is a transition metal complex having at least one ligand or part of a ligand if the ligand is more than bidentate, where the more than bidentate ligand is selected from the group consisting of:

wherein R_(a), R_(b), R_(c), and R_(d) may represent mono, di, tri, or tetra substitution, or no substitution; and wherein R_(a), R_(b), R_(c), and R_(d) are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein two adjacent substituents of R_(a), R_(b), R_(c), and R_(d) are optionally joined to form a fused ring or form a multidentate ligand.

In some embodiments, the organic layer in the first device is a hole injecting layer or a hole transporting layer. In some other embodiments, the organic layer is an electron injecting layer or an electron transporting layer. In some embodiments, the organic layer is an exciton blocking layer or a charge blocking layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does not have a separate electron transport layer.

FIG. 3 shows an embodiment of a boron-nitrogen heterocycle

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an “exciton,” which is a localized electron-hole pair having an excited energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the exciton may be localized on an excimer or an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also occur, but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from their singlet states (“fluorescence”) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.

More recently, OLEDs having emissive materials that emit light from triplet states (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, vol. 395, 151-154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.

FIG. 1 shows an organic light emitting device 100. The figures are not necessarily drawn to scale. Device 100 may include a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, an emissive layer 135, a hole blocking layer 140, an electron transport layer 145, an electron injection layer 150, a protective layer 155, a cathode 160, and a barrier layer 170. Cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164. Device 100 may be fabricated by depositing the layers described, in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporated by reference.

More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210, a cathode 215, an emissive layer 220, a hole transport layer 225, and an anode 230. Device 200 may be fabricated by depositing the layers described, in order. Because the most common OLED configuration has a cathode disposed over the anode, and device 200 has cathode 215 disposed under anode 230, device 200 may be referred to as an “inverted” OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layers of device 200. FIG. 2 provides one example of how some layers may be omitted from the structure of device 100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided by way of non-limiting example, and it is understood that embodiments of the invention may be used in connection with a wide variety of other structures. The specific materials and structures described are exemplary in nature, and other materials and structures may be used. Functional OLEDs may be achieved by combining the various layers described in different ways, or layers may be omitted entirely, based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than those specifically described may be used. Although many of the examples provided herein describe various layers as comprising a single material, it is understood that combinations of materials, such as a mixture of host and dopant, or more generally a mixture, may be used. Also, the layers may have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. For example, in device 200, hole transport layer 225 transports holes and injects holes into emissive layer 220, and may be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED may be described as having an “organic layer” disposed between a cathode and an anode. This organic layer may comprise a single layer, or may further comprise multiple layers of different organic materials as described, for example, with respect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in FIGS. 1 and 2. For example, the substrate may include an angled reflective surface to improve out-coupling, such as a mesa structure as described in U.S. Pat. No. 6,091,195 to Forrest et al., and/or a pit structure as described in U.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated by reference in their entireties.

Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP), such as described in U.S. patent application Ser. No. 10/233,470, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink jet and OVJD. Other methods may also be used. The materials to be deposited may be modified to make them compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3-20 carbons is a preferred range. Materials with asymmetric structures may have better solution processibility than those having symmetric structures, because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the present invention may further optionally comprise a barrier layer. One purpose of the barrier layer is to protect the electrodes and organic layers from damaging exposure to harmful species in the environment including moisture, vapor and/or gases, etc. The barrier layer may be deposited over, under or next to a substrate, an electrode, or over any other parts of a device including an edge. The barrier layer may comprise a single layer, or multiple layers. The barrier layer may be formed by various known chemical vapor deposition techniques and may include compositions having a single phase as well as compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may incorporate an inorganic or an organic compound or both. The preferred barrier layer comprises a mixture of a polymeric material and a non-polymeric material as described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos. PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporated by reference in their entireties. To be considered a “mixture”, the aforesaid polymeric and non-polymeric materials comprising the barrier layer should be deposited under the same reaction conditions and/or at the same time. The weight ratio of polymeric to non-polymeric material may be in the range of 95:5 to 5:95. The polymeric material and the non-polymeric material may be created from the same precursor material. In one example, the mixture of a polymeric material and a non-polymeric material consists essentially of polymeric silicon and inorganic silicon.

Devices fabricated in accordance with embodiments of the invention may be incorporated into a wide variety of consumer products, including flat panel displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads up displays, fully transparent displays, flexible displays, laser printers, telephones, cell phones, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, micro-displays, vehicles, a large area wall, theater or stadium screen, or a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present invention, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees C., and more preferably at room temperature (20-25 degrees C.).

The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl, heterocyclic group, aryl, aromatic group, and heteroaryl are known to the art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32, which are incorporated herein by reference.

Aromatic six-membered boron-nitrogen heterocycles that are isoelectronic with benzene can have significantly different properties in comparison to their carbocyclic analogues, especially where the heterocycle contains a single B—N substitution. Examples of such compounds include 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, and substituted variants thereof. Embodiments of the present invention include polycyclic boron-nitrogen heterocycles, which have more complex structures than azaborine. In many instances, such polycyclic boron-nitrogen heterocycles can exhibit desirable photophyscical and electrochemical properties, particularly in comparison to their analogues that lack a B—N bond. This may be due at least in part to the strong dipole moment, which is induced by the effect of the boron-nitrogen substitution on the overall electronegativity and resonance of the resulting compound.

Polycyclic boron-nitrogen heterocycles can be synthesized by extending and modifying the principles described in Liu et al., Ang. Chem. Int. Ed., vol. 51, pp. 6074-6092 (2012) and Abbey et al., J. Am. Chem. Soc., vol. 133, pp. 11508-11511 (2011), each of which is incorporated herein by reference in its entirety.

Carbazole and carbazole-containing compounds can serve as an important building block for organic electronic materials. For example, carbazole-containing compounds can be used as: host materials for both fluorescent and phosphorescent OLEDs; fluorescent emitters; photoconductors; and active materials for organic TFTs and solar cells. Incorporating B—N into a carbazole structure, as shown below, can yield certain beneficial properties. For example, the HOMO/LUMO energy levels and photophysical properties can be modified due to the donor-acceptor nature of the B—N structure, which may make such compounds more suitable for applications in organic electronic devices.

Certain applications may require a lower triplet energy than that provided by carbazole or a carbazole-containing compound. Thus, in such instances, the use of a B—N substituted carbazole can lead to a lower triplet and increased stabilization. Such changes can lead to a more balanced charge transport profile, and can also provide for better injection properties.

In at least one aspect, the invention provides boron-nitrogen heterocycles having the Formula (I):

wherein one of the E₁ and E₂ is N, and one of the E₁ and E₂ is B; wherein E₃ and E₄ is carbon; wherein ring Y and ring Z are 5-membered or 6-membered carbocyclic or heterocyclic aromatic ring fused to ring X; wherein R₂ and R₃ represent mono, di, tri, tetra substitutions or no substitution; wherein R₂ and R₃ are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R₁ is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein any two adjacent R₂, and R₃ are optionally joined to form a ring, which may be further substituted.

In some embodiments, E₁ is B, and E₂ is N. In some other embodiments, E₁ is N, and E₂ is B.

In some embodiments, ring Y is selected from the group consisting of:

wherein E₅ is selected from the group consisting of NR, O, S, and Se; and wherein R is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. In some further embodiments, ring Y is

In some embodiments, ring Z is selected from the group consisting of:

wherein E₅ is selected from the group consisting of NR, O, S, and Se; and wherein R is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof. In some further embodiments, ring Z is

In some embodiments, R₁, R₂, and R₃ are independently selected from the group consisting of phenyl, pyridine, triazine, pyrimidine, phenanthrene, naphthalene, anthracene, triphenylene, pyrene, chrysene, fluoranthene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene, each of which may be further substituted.

In some embodiments, the boron-nitrogen heterocycles have the formula

where the variables have the meanings defined above.

In some embodiments, the boron-nitrogen heterocycles have Formula (II):

wherein R²¹ and R²² are independently are aryl or heteroaryl, each of which may be further substituted; R²³ and R²⁴ are independently aryl or heteroaryl, each of which may be further substituted; and G is arylene, heteroarylene, or combinations thereof. In some such embodiments, G is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof. In some embodiments, such compounds are hole injection or hole transporting materials.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is

In some embodiments, the bron-nitrogen heterocycle is a compound having Formula (III):

wherein R³¹ and R³² independently are aryl or heteroaryl, which may be further substituted; and wherein G¹, G², and G³ independently are arylene or heteroarylene. In some such embodiments, G¹, G², and G³ independently are phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof. In some embodiments, such compounds are hole injection or hole transporting materials.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is: which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (IV):

wherein G⁴ is arylene or heteroarylene. In some such embodiments, G⁴ is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof. In some embodiments, such compounds are host materials.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (V):

wherein R⁵¹ is aryl or heteroaryl. In some such embodiments, R⁵¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof. In some embodiments, such compounds are host materials. In some other embodiments, such compounds are fluorescent emitters.

In some embodiments, the born-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (VI):

wherein R⁶¹ and R⁶² independently are aryl or heteroaryl. In some such embodiments, R⁶¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof; and R⁶² is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof. In some embodiments, such compounds are host materials. In some other embodiments, such compounds are fluorescent emitters.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (VII):

wherein R⁷¹ and R⁷² independently are aryl or heteroaryl. In some such embodiments, R⁷¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof; and R⁷² is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof. In some embodiments, such compounds are host materials.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In some embodiments, the boron-nitrogen heterocycle is a compound having Formula (VIII):

wherein G⁵ is arylene or heteroarylene; and R⁸¹ and R⁸² are independently aryl or heteroaryl, each of which is substituted with at least one acyclic or cyclic aliphatic substituent. In some such embodiments, G⁵ is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof. In some embodiments, such compounds are fluorescent emitters.

In some embodiments, the boron-nitrogen heterocycle is a compound, which is:

In another aspect, the invention provides devices that include boron-nitrogen heterocycles, such as those described in the foregoing paragraphs. In some embodiments, the invention provides a first device comprising a first organic light emitting device, which further comprises: an anode; a cathode; and an organic layer disposed between the anode and the cathode, which comprises a boron-nitrogen heterocycle according to any of the above embodiments. In some embodiments, the first device is a consumer product. In some embodiments, the first device is an organic light emitting device (OLED). In some embodiments, the first device comprises a lighting panel.

The boron-nitrogen heterocycles can serve various roles within a device. In some embodiments, the first device comprises an organic layer that is an emissive layer, where the emissive layer comprises an emissive dopant, which is a boron-nitrogen heterocycle of any of the above embodiments. In some such embodiments, the first device is a delayed fluorescence device.

In some other embodiments, the first device comprises an organic layer that is an emissive layer, and also comprises a host. In some such embodiments, the host is a boron-nitrogen heterocycle of any of the above embodiments. In some such embodiments, the organic layer comprises an emissive dopant. In some embodiments, the emissive dopant is a fluorescent dopant. In some embodiments, the emissive dopant is a transition metal complex having at least one ligand or part of a ligand if the ligand is more than bidentate, where the more than bidentate ligand is selected from the group consisting of:

wherein R_(a), R_(b), R_(c), and R_(d) may represent mono, di, tri, or tetra substitution, or no substitution; and wherein R_(a), R_(b), R_(c), and R_(d) are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein two adjacent substituents of R_(a), R_(b), R_(c), and R_(d) are optionally joined to form a fused ring or form a multidentate ligand.

In some embodiments, the organic layer in the first device is a hole injecting layer or a hole transporting layer. In some other embodiments, the organic layer is an electron injecting layer or an electron transporting layer. In some embodiments, the organic layer is an exciton blocking layer or a charge blocking layer.

Combination with Other Materials

The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the present invention is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material. Examples of the material include, but not limit to: a phthalocyanine or porphryin derivative; an aromatic amine derivative; an indolocarbazole derivative; a polymer containing fluorohydrocarbon; a polymer with conductivity dopants; a conducting polymer, such as PEDOT/PSS; a self-assembly monomer derived from compounds such as phosphonic acid and sliane derivatives; a metal oxide derivative, such as MoO_(x); a p-type semiconducting organic compound, such as 1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and a cross-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, but not limit to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each Ar is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the group consisting of:

k is an integer from 1 to 20; X¹⁰¹ to X¹⁰⁸ is C (including CH) or N; Z¹⁰¹ is NAr¹, O, or S; Ar¹ has the same group defined above.

Examples of metal complexes used in HIL or HTL include, but not limit to the following general formula:

Met is a metal; (Y¹⁰¹-Y¹⁰²) is a bidentate ligand, Y¹⁰¹ and Y¹⁰² are independently selected from C, N, O, P, and S; L¹⁰¹ is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, (Y¹⁰¹-Y¹⁰²) is a 2-phenylpyridine derivative. In another aspect, (Y¹⁰¹-Y¹⁰²) is a carbene ligand. In another aspect, Met is selected from Ir, Pt, Os, and Zn. In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc⁺/Fc couple less than about 0.6 V.

Host:

The light emitting layer of the organic EL device of the present invention preferably contains at least a metal complex as light emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complexes or organic compounds may be used as long as the triplet energy of the host is larger than that of the dopant. While the Table below categorizes host materials as preferred for devices that emit various colors, any host material may be used with any dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have the following general formula:

Met is a metal; (Y¹⁰³-Y¹⁰⁴) is a bidentate ligand, Y¹⁰³ and Y¹⁰⁴ are independently selected from C, N, O, P, and S; L¹⁰¹ is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.

In one aspect, the metal complexes are:

(O—N) is a bidentate ligand, having metal coordinated to atoms O and N. In another aspect, Met is selected from Ir and Pt. In a further aspect, (Y¹⁰³-Y¹⁰⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the group consisting aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; group consisting aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and group consisting 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Wherein each group is further substituted by a substituent selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

In one aspect, host compound contains at least one of the following groups in the molecule:

R¹⁰¹ to R¹⁰⁷ is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above.

k is an integer from 1 to 20; k′″ is an integer from 0 to 20.

X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) or N.

Z¹⁰¹ and Z¹⁰² is selected from NR¹⁰¹, O, or S.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED.

In one aspect, compound used in HBL contains the same molecule or the same functional groups used as host described above. In another aspect, compound used in HBL contains at least one of the following groups in the molecule:

k is an integer from 1 to 20; L¹⁰¹ is another ligand, k′ is an integer from 1 to 3.

ETL:

Electron transport layer (ETL) may include a material capable of transporting electrons. Electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.

In one aspect, compound used in ETL contains at least one of the following groups in the molecule:

R¹⁰¹ is selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. Ar¹ to Ar³ has the similar definition as Ar's mentioned above. k is an integer from 1 to 20. X¹⁰¹ to X¹⁰⁸ is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL contains, but not limit to the following general formula:

(O—N) or (N—N) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L¹⁰¹ is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device, the hydrogen atoms can be partially or fully deuterated. Thus, any specifically listed substituent, such as, without limitation, methyl, phenyl, pyridyl, etc. encompasses undeuterated, partially deuterated, and fully deuterated versions thereof. Similarly, classes of substituents such as, without limitation, alkyl, aryl, cycloalkyl, heteroaryl, etc. also encompass undeuterated, partially deuterated, and fully deuterated versions thereof.

In addition to and/or in combination with the materials disclosed herein, many hole injection materials, hole transporting materials, host materials, dopant materials, exciton/hole blocking layer materials, electron transporting and electron injecting materials may be used in an OLED. Non-limiting examples of the materials that may be used in an OLED in combination with materials disclosed herein are listed in Table 1 below. Table 1 lists non-limiting classes of materials, non-limiting examples of compounds for each class, and references that disclose the materials.

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EXPERIMENTAL Example 1 Compound Synthesis

The boron-nitrogen heterocycles can be made by any suitable method. In some embodiments, such compounds can be made in a manner consistent with Scheme 1, shown on the following page.

Such methods may be modified as applied to the synthesis of any particular compound, based on the knowledge of persons of skill in the art.

Example 2 Computational Examples

DFT calculations with the Gaussian software package at the B3LYP/cep-31g functional and basis set were carried out for the compounds shown below in TABLE 2, below. TABLE 2 shows the calculated values for the HOMO and the LUMO, and shows the respective HOMO-LUMO gap, as well as the wavelengths of light corresponding to the singlet S₁ and triplet T₁ transitions and the calculated dipole of the compounds. The boron-nitrogen heterocycle showed stabilization of the triplet (T₁) state without any significant change in the singlet (S₁) state relative to carbazole.

HOMO LUMO Dipole Compound Structure (eV) (eV) Gap (eV) (debye) T₁ (nm) S₁ (nm)

−5.51 −0.80 4.70 0.44 430 298

−5.44 −0.64 4.80 1.65 389 299

It is understood that the various embodiments described herein are by way of example only, and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted with other materials and structures without deviating from the spirit of the invention. The present invention as claimed may therefore include variations from the particular examples and preferred embodiments described herein, as will be apparent to one of skill in the art. It is understood that various theories as to why the invention works are not intended to be limiting. 

The invention claimed is:
 1. A compound having the Formula (I):

wherein one of the E₁ and E₂ is N, and one of the E₁ and E₂ is B; wherein E₃ and E₄ is carbon; wherein ring Y and ring Z are 5-membered or 6-membered carbocyclic or heterocyclic aromatic ring fused to ring X; wherein ring Y is selected from the group consisting of:

wherein E₅ is selected from the group consisting of NR, O, S, and Se; and wherein R is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R₂ and R₃ represent mono, di, tri, tetra substitutions or no substitution; wherein R₂ and R₃ are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R₁ is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein any two adjacent R₂, and R₃ are optionally joined to form a ring, which may be further substituted.
 2. The compound of claim 1, wherein E₁ is B, and E₂ is N.
 3. The compound of claim 1, wherein E₁ is N, and E₂ is B.
 4. The compound of claim 1, wherein ring Y is


5. The compound of claim 1, wherein ring Z is selected from the group consisting of:

wherein E₅ is selected from the group consisting of NR, O, S, and Se; and wherein R is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
 6. The compound of claim 1, wherein ring Z is


7. The compound of claim 1, wherein R₁, R₂, and R₃ are independently selected from the group consisting of phenyl, pyridine, triazine, pyrimidine, phenanthrene, naphthalene, anthracene, triphenylene, pyrene, chrysene, fluoranthene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene, each of which may be further substituted.
 8. The compound of claim 1, wherein the compound has the formula


9. The compound of claim 1, wherein the compound is a compound having Formula (II):

wherein R²¹ and R²² are independently are aryl or heteroaryl, each of which may be further substituted; R²³ and R²⁴ are independently aryl or heteroaryl, each of which may be further substituted; and G is arylene, heteroarylene, or combinations thereof.
 10. The compound of claim 9, wherein G is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.
 11. The compound of claim 10, which is


12. The compound of claim 1, wherein the compound is a compound having Formula (III):

wherein R³¹ and R³² independently are aryl or heteroaryl, which may be further substituted; wherein G¹, G², and G³ independently are arylene or heteroarylene.
 13. The compound of claim 12, wherein G¹, G², and G³ independently are phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.
 14. The compound of claim 13, which is:


15. The compound of claim 1, wherein, the compound is a compound having Formula (IV):

wherein G⁴ is arylene or heteroarylene.
 16. The compound of claim 15, wherein G⁴ is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.
 17. The compound of claim 16, which is:


18. The compound of claim 1, wherein the compound is a compound of Formula (V)

wherein R⁵¹ is aryl or heteroaryl.
 19. The compound of claim 18, wherein R⁵¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.
 20. The compound of claim 18, which is:


21. The compound of claim 1, wherein the compound is a compound of Formula (VI)

wherein R⁶¹ and R⁶² independently are aryl or heteroaryl.
 22. The compound of claim 21, wherein: R⁶¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof; and R⁶² is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.
 23. The compound of claim 22, which is:


24. The compound of claim 1, wherein the compound is a compound of Formula (VII)

wherein R⁷¹ and R⁷² independently are aryl or heteroaryl.
 25. The compound of claim 24, wherein: R⁷¹ is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof; and R⁷² is phenyl, pyridyl, biphenylyl, triazinyl, pyrimidinyl, triphenylyl, naphthyl, anthracenyl, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.
 26. The compound of claim 25, which is:


27. The compound of claim 1, where the compound is a compound having Formula (VIII):

wherein G⁵ is arylene or heteroarylene; and R⁸¹ and R⁸² are independently aryl or heteroaryl, each of which is substituted with at least one acyclic or cyclic aliphatic substituent.
 28. The compound of claim 27, wherein G⁵ is phenylene, pyridine, biphenylene, triazine, pyrimidine, triphenylene, naphthylene, anthracene, chrysene, pyrene, fluoranthene, phenanthrene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, aza-carbazole, aza-dibenzothiphene, aza-dibenzofuran, aza-debenzoselenophene, or combinations thereof.
 29. The compound of claim 27, which is:


30. A first device comprising a first organic light emitting device, which further comprises: an anode; a cathode; and an organic layer disposed between the anode and the cathode comprising a compound having the Formula (I):

wherein one of the E₁ and E₂ is N, and one of the E₁ and E₂ is B; wherein E₃ and E₄ is carbon; wherein ring Y and ring Z are 5-membered or 6-membered carbocyclic or heterocyclic aromatic ring fused to ring X; wherein ring Y is selected from the group consisting of:

wherein E₅ is selected from the group consisting of NR, O, S, and Se; and wherein R is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R₂ and R₃ represent mono, di, tri, tetra substitutions or no substitution; wherein R₂ and R₃ are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R₁ is selected from the group consisting of halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein any two adjacent R₂, and R₃ are optionally joined to form a ring, which may be further substituted.
 31. The first device of claim 30, wherein the first device is a consumer product.
 32. The first device of claim 30, wherein the first device is an organic light-emitting device.
 33. The first device of claim 30, wherein the first device comprises a lighting panel.
 34. The first device of claim 30, wherein the organic layer is an emissive layer and the compound of Formula (I) is an emissive dopant.
 35. The first device of claim 34, where the device is a delayed fluorescence device.
 36. The first device of claim 30, wherein the organic layer is an emissive layer and the compound of Formula (I) is a host.
 37. The first device of claim 36, wherein the emissive layer further comprises a fluorescent emissive dopant.
 38. The first device of claim 36, wherein the emissive layer further comprises an emissive dopant, which is a transition metal complex having at least one ligand or part of the ligand, if the ligand is more than bidentate, selected from the group consisting of:

wherein R_(a), R_(b), R_(c), and R_(d) may represent mono, di, tri, or tetra substitution, or no substitution; and wherein R_(a), R_(b), R_(c), and R_(d) are independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein two adjacent substituents of R_(a), R_(b), R_(c), and R_(d) are optionally joined to form a fused ring or form a multidentate ligand.
 39. The first device of claim 30, wherein the organic layer is a hole injecting layer or a hole transporting layer.
 40. The first device of claim 30, wherein the organic layer is an electron injecting layer or an electron transporting layer.
 41. The first device of claim 30, wherein the organic layer is an exciton blocking layer or a charge blocking layer. 